161231761 has 4 divisors (see below), whose sum is σ = 164662272. Its totient is φ = 157801252.

The previous prime is 161231737. The next prime is 161231767. The reversal of 161231761 is 167132161.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 161231761 - 2⁵ = 161231729 is a prime.

It is a super-2 number, since 2×161231761² = 51991361510322242, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161231767) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1715185 + ... + 1715278.

It is an arithmetic number, because the mean of its divisors is an integer number (41165568).

Almost surely, 2^161231761 is an apocalyptic number.

It is an amenable number.

161231761 is a deficient number, since it is larger than the sum of its proper divisors (3430511).

161231761 is an equidigital number, since it uses as much as digits as its factorization.

161231761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3430510.

The product of its digits is 1512, while the sum is 28.

The square root of 161231761 is about 12697.7069189677. The cubic root of 161231761 is about 544.2730942550.

The spelling of 161231761 in words is "one hundred sixty-one million, two hundred thirty-one thousand, seven hundred sixty-one".